What would be the concerns? You'd need a manifold to enable several hoses(guns) or at the minimum a three way tee. I imagine you'd need a way for water to be going into the pool when guns not in use to avoid damage to pump. Maybe easiest to accomplish at the guns, when you pull trigger you are narrowing the hole the water comes through, or diverting it's path to gun nozzle. Then you'd want to be sure you don't damage the Polaris connection point in pools side. Don't want to get tangled up in hoses.
Maybe poolside mounted turrets would be better, like the air powered ones that shoot Nurf balls at kids play places?
Maybe just stick with super soakers?
I guess if you used one return and you had another one or two you might be less concerned about pump damage?
Might be Easiest to alter a squirt gun, attaching pressure hose to it's tank?